Objective Development Forums

can any one tell me how to build 100 uH coil.
what is the guage and core diameter, and how many turns should have it...

please help me....

The aproximate inductance of a air core inductor is L(uH)=(d^2*n^2)/(18*d+40*l).
The inductance is in microHenries, d is the diameter in inches, l is the lenght in inches and n is the number of turns. This is valid if l (the lenght) is greater or equal to 4*d.
To determine the wire to be used, you need the wire diameter (d1) and tne desired length l, so you have another equation: l=d1*n.

I hope this help you, but belive me, it's a better idea to get one from some old board, or buying one. In an electronics curse whe must make one inductor for an collpits oscilator, and the results are not so good as you expected.

Regards from uy (Uruguay).
Diego Bouvier.

I forget to mention that the problem making an air core inductor is the size. If you use ferrite (or other material) in the core, you need less number of wire turns to get se same result.

Regards.
Diego Bouvier

Thanks mate,i just got this message.
thushara